title: Factor analysis of responses to thermal, electrical, and mechanical painful stimuli supports the importance of multi-modal pain assessment.
abstract: During the last decade, a multi-modal approach has been established in human experimental pain research for assessing pain thresholds and responses to various experimental pain modalities. Studies have concluded that differences in responses to pain stimuli are mainly related to variation between individuals rather than variation in response to different stimulus modalities. In a factor analysis of 272 consecutive volunteers (137 men and 135 women) who underwent tests with different experimental pain modalities, it was determined whether responses to different pain modalities represent distinct individual uncorrelated dimensions of pain perception. Volunteers underwent single painful electrical stimulation, repeated painful electrical stimulation (temporal summation), test for reflex receptive field, pressure pain stimulation, heat pain stimulation, cold pain stimulation, and a cold pressor test (ice water test). Five distinct factors were found representing responses to 5 distinct experimental pain modalities: pressure, heat, cold, electrical stimulation, and reflex-receptive fields. Each of the factors explained approximately 8% to 35% of the observed variance, and the 5 factors cumulatively explained 94% of the variance. The correlation between the 5 factors was near null (median ρ=0.00, range -0.03 to 0.05), with 95% confidence intervals for pairwise correlations between 2 factors excluding any relevant correlation. Results were almost similar for analyses stratified according to gender and age. Responses to different experimental pain modalities represent different specific dimensions and should be assessed in combination in future pharmacological and clinical studies to represent the complexity of nociception and pain experience.
authors.affiliation: University Department of Anaesthesiology and Pain Therapy, Bern University Hospital, Inselspital, Bern, Switzerland Division of Clinical Epidemiology and Biostatistics, Institute of Social and Preventive Medicine, University of Bern, Switzerland, and Clinical Trial Unit (CTU) Bern, Bern University Hospital, Inselspital, Bern, Switzerland DeFiMS, School of Oriental and African Studies (SOAS), University of London, London, United Kingdom, and DEI, University of Rome Tor Vergata, Rome, Italy Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
authors.forename: Alban Y
authors.initials: AY
authors.lastname: Neziri
authors.forename: Michele
authors.initials: M
authors.lastname: Curatolo
authors.forename: Eveline
authors.initials: E
authors.lastname: Nüesch
authors.forename: Pasquale
authors.initials: P
authors.lastname: Scaramozzino
authors.forename: Ole K
authors.initials: OK
authors.lastname: Andersen
authors.forename: Lars
authors.initials: L
authors.lastname: Arendt-Nielsen
authors.forename: Peter
authors.initials: P
authors.lastname: Jüni
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004558:Electric Stimulation / Q000009:adverse effects; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000145:classification* / Q000175:diagnosis* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D010147:Pain Measurement / Q000379:methods*; D017288:Pain Threshold / Q000502:physiology*; D010812:Physical Stimulation / Q000009:adverse effects*; D011601:Psychophysics; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D013223:Statistics as Topic; D013696:Temperature; D055815:Young Adult